1. Field of the Invention
This invention relates to a control circuit for bar graph display panels.
2. Description of the Prior Art
It has heretofore been proposed to provide bar graph display panels that provide analog displays with digital accuracy, these being useful for process control and other purposes. The display panels had low cost drive circuitry and low power consumption.
The bar graph panels are constructed of a rear substrate, spacer and glass front plate with a desired segment pattern screened onto the substrate using a conductive ink, a black dielectric mask screened onto the substrate. The front glass has two transparent anodes applied for dual linear bar graph displays. The interior space is sealed and filled with a neon gas mixture. Panel connections are made through a connector assembly between the glass and the substrate and which mates with printed contacts on one end of the panel. Structures of this type are available from Burroughs Corporation, Electronic Components Division, Plainfield, New Jersey, and such a panel is shown in U.S. Patent to Maloney, No. 3,973,166 and controls for such a panel are shown in Saxon, U.S. Pat. No. 3,967,158.
The drive circuits for the bar graph display panels heretofore available had various shortcomings, including the tendency to drift, which are overcome with the control circuitry of the present invention.